Thin film capacitor

Abstract

The utility model provides a film capacitor, comprising: at least two cores arranged side by side, each core having a first end and a second end opposite to each other and a side surface extending between the first end and the second end, the second end being provided with an electrode; the conductive first busbar comprises a first electrical interface, a first section, a second section, a third section and a connecting sheet, the first section covers the first end and is connected between the first electrical interface and the third section, and the second section covers the second end and is electrically connected with the electrode on the second end; the third section covers one side surface of the core and is connected between the first section and the second section; the connecting piece is connected with the first section and the electrode of the second end of the core farthest from the first electrical interface and extends to pass through the side face of the core farthest from the first electrical interface, and the connecting piece is spaced from the third section.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of capacitors, in particular to a thin-film capacitor. BACKGROUND

[0002] The DC-link system for new energy vehicles is a key component in the power electronic system of new energy vehicles, which mainly undertakes the important role of stabilizing the DC bus voltage, improving system efficiency and reliability. Thin-film capacitors are usually used in vehicle inverters because of their non-polarity, high insulation resistance, high temperature resistance, good stability and other advantages, and are one of the key components in the DC-link system.

[0003] In known thin-film capacitors, a single thin-film capacitor usually includes multiple cores. Therefore, the current flow path of the current from the electrical interface to each core in the thin-film capacitor usually has different lengths.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. CONTENT OF THE INVENTION

[0005] According to different aspects, one of the purposes of the present application is to solve the problem of heat concentration of some cores of the thin-film capacitor.

[0006] In addition, the present application also aims to solve or alleviate other technical problems existing in the prior art.

[0007] According to an aspect of the present application, there is provided:

[0008] at least two cores arranged side by side, each core having opposite first and second ends and a side extending between the first and second ends, an electrode being provided on the second end;

[0009] a conductive first busbar including a first electrical interface, a first section, a second section, a third section, and a connecting piece, the first section covering the first end and being connected between the first electrical interface and the third section, the second section covering the second end and electrically connecting the electrode on the second end, the third section covering one side of the core and being connected between the first section and the second section;

[0010] the connecting piece connects the first section and the electrode of the second end of the core farthest from the first electrical interface and extends through the side of the core farthest from the first electrical interface, the connecting piece being spaced apart from the third section.

[0011] The benefits of the present application include:

[0012] The film capacitor of this application uses an additional connecting piece to guide the current through the side of the core farthest from the electrical interface, shortening the current flow path of the core farthest from the electrical interface, allowing the current to be more evenly distributed to each core, thereby preventing some cores from being overloaded. It also significantly reduces the hot spot temperature, helping to improve the service life and reliability of the film capacitor and reduce performance degradation or failure caused by overheating. In addition, this design of the film capacitor innovatively solves the problem of heat concentration in the DC-link system, providing a more reliable and efficient solution for the DC-link system of new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other features of the present application will become apparent with reference to the accompanying drawings, in which:

[0014] Figure 1 A schematic structural diagram of a thin film capacitor according to one embodiment of the present application is shown;

[0015] Figure 2 A schematic diagram of the structure of a thin film capacitor according to one embodiment of the present application after removing the second busbar and the insulating layer, and a current path flowing to the core are shown;

[0016] Figure 3 FIG. 1 shows a view of a thin film capacitor according to an embodiment of the present application viewed from another direction. DETAILED DESCRIPTION

[0017] It is easy to understand that, based on the technical solution of this application, without changing the essential spirit of this application, a person skilled in the art can propose a variety of interchangeable structural methods and implementation methods. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of this application and should not be regarded as the entire application or as a limitation or restriction of the technical solution of this application.

[0018] The terms "up," "down," "left," "right," "front," "back," "front," "back," "top," and "bottom" mentioned or potentially mentioned in this specification are defined relative to the configurations shown in the accompanying drawings. These are relative concepts and may vary depending on the location or usage of the device. Therefore, these or other directional terms should not be construed as restrictive. Furthermore, the terms "first," "second," "third," and similar expressions are used solely for descriptive and distinguishing purposes and should not be construed as indicating or implying the relative importance of the corresponding components or the order or sequence of their assembly.

[0019] Known film capacitors usually include multiple cores to meet the high inductance requirements of the capacitor. These cores are arranged in rows, for example, so that it is difficult for each core to be exactly the same distance from the electrical interface. Therefore, for each core in a film capacitor with multiple cores, there are usually current paths of different lengths. Especially for the core farthest from the electrical interface, its current path is too long. Under high-frequency operation, the equivalent series inductance (ESL) will be too large, making it difficult for current to flow into it, which may cause other cores to bear too much current and overload during operation, and make the hot spot temperature of the film capacitor too high, causing its heat concentration problem, thereby increasing the thermal risk of the film capacitor and reducing its service life.

[0020] The film capacitor of the present application provides a "shortcut" for current to flow to the core at the core farthest from the electrical interface by adding a connecting plate, shortening the current path from the electrical interface to the core, so that the current can be distributed more evenly among the cores, reducing the temperature rise of the capacitor and preventing the capacitor from having thermal problems such as excessively high local hot spots.

[0021] refer to Figure 1 , which shows a schematic structural diagram of a thin film capacitor 10 proposed according to one embodiment of the present application. Figure 1 The film capacitor 10 in the figure actually includes two identical film capacitor units 100 and 200, which are connected to each other via electrical interfaces 144, 151, and 152. The electrical interfaces 144, 151, and 152 can be connected to an external circuit to provide current to the film capacitor 10. It should be understood that the film capacitor 10 can also include only one of the film capacitor units 100. Therefore, the structure of the film capacitor 10 is first described with respect to one film capacitor unit 100.

[0022] for Figure 1 For example, a single film capacitor unit 100 includes three cores 110, 120, and 130, a conductive first busbar 140, and a second busbar 150. Each core has a first end 101 and a second end 102, and a side extending between the first end 101 and the second end 102. Electrodes are provided at these two ends, or each end is entirely provided as an electrode. Figure 1In an embodiment, the first end 101 and the second end 102 are each provided as an electrode, for example the first end 101 is provided as a positive electrode and the second end 102 is provided as a negative electrode. It is to be understood that the core can also be arranged such that the first end 101 is the negative end and the second end 102 is the positive end, which does not affect the arrangement of the busbar. The three cores 110, 120, 130 are arranged side by side. The first busbar 140 comprises in its structure a first section 141, a second section 142, a third section 143, a first electrical interface 144 and a connecting tab 145. The first section 141 covers the first end 101 of each core and is connected between the first electrical interface 144 and the third section 143, the second section 142 covers the second end 102 and electrically connects the electrode on the second end 102, the third section 143 is formed by bending the first busbar 140, which extends past the first side 131 of the core and is connected between the first section 141 and the second section 142. The first electrical interface 144 is connected to the first section 141. Thereby, current flowing in from the first electrical interface 144 can flow to the second end 102 of the core. The connecting tab 145 connects the first section 141 and the electrode of the second end 102 of the core 130 farthest from the first electrical interface 144 and extends past the side 132 of the core 130 farthest from the first electrical interface 144, the connecting tab 145 is arranged spaced apart from the third section 143.

[0023] The second busbar 150 comprises a main section 153 and second electrical interfaces 151, 152 connected to the main section 153. The main section 153 of the second busbar 150 is electrically connected to the electrode of the first end 101 of each core and is arranged below the first section 141 of the first busbar 140, the second electrical interfaces 151, 152 are connected to the edges of the main section 153. Thereby, current flowing in from the second electrical interfaces 151, 152 can first flow to the first end 101 of the core. For the film capacitor unit 100, current can flow in from the first electrical interface 144, to the second end 102 of the core, then out through the first end 101 of the core, finally to the second electrical interfaces 151, 152 and out from the second electrical interfaces 151, 152, or current can flow in from the second electrical interfaces 151, 152, to the first end 101 of the core, then out through the second end 102 of the core, finally to the first electrical interface 144 and out from the first electrical interface 144.

[0024] It should be understood that the "electrical interface" described in this application refers to the part where current enters and exits the entire thin film capacitor, and is also the part where all the cores in the thin film capacitor converge. It acts as a conductive component and can be set in the form of an interface, or in the form of connectors such as pins or connecting terminals. Those skilled in the art can choose the type of "electrical interface" component according to the different forms of thin film capacitors, and these types should all be covered within the concept of "electrical interface".

[0025] In one embodiment of the present application, an insulating layer 160 is interposed between the first section 141 of the first busbar 140 and the second busbar 150 to prevent a short circuit between the second busbar 150 and the first busbar 140 .

[0026] exist Figure 1 As can be seen in the embodiment, the current path from the second electrical interfaces 151 and 152 through the main section 153 of the second busbar 150 to the first end 101 is relatively short. Therefore, when the number of cores is small, for example, when the number of cores is only 2-4, the difference in the current path from the second electrical interfaces 151 and 152 through the main section 153 of the second busbar 150 to the first end 101 of each core is also small. However, if the connecting piece 145 is not provided, the current path from the first electrical interface 144 through the first busbar 140 to the second end 102 is longer, and the current path from the first electrical interface 144 to the second end 102 of each core also varies greatly. Therefore, if the connecting piece 145 is not provided, the current path from the first electrical interface 144 to the second end 102 of each core has a large difference in length, making it difficult to evenly distribute the current among the cores.

[0027] Will Figure 1 The three cores in the embodiment are defined as a first core 110, a second core 120 and a third core 130. Figure 1 As can be seen in FIG, the first electrical interface 144 is arranged closer to the first core 110, that is, the first electrical interface 144 is closest to the first core 110 and farthest from the third core 130. Figure 2Fig. 2 shows a schematic view of the structure of the film capacitor 10 according to one embodiment of the present application, after removing the second busbar 150 and the insulating layer 160, and the current paths to the cores. The current path 1 (schematically shown with red arrows) is the current path from the first electrical interface 144 to the second end 102 of the first core 110, and the current path 3 (schematically shown with yellow arrows) is the current path from the first electrical interface 144 to the second end 102 of the third core 130 when no connecting piece 145 is provided. It can be seen that, due to the closer distance between the first electrical interface 144 and the first core 110, the current path 3 is longer than the current path 1, and the current is more likely to flow to the first core 110 and the second core 120 (the current path from the first electrical interface 144 to the second end 102 of the second core 120 is approximately the same as the current path 1). In order to shorten the length of the current path from the first electrical interface 144 to the third core 130 (the core farthest from the first electrical interface 144), and make it as close as possible to the length of the current path from the first electrical interface 144 to the first core 110, a connecting piece 145 is provided on the side of the core farthest from the first electrical interface 144 (here, the third core 130), which connects the first section 141 of the first busbar 140 and the second end 102 of the core. Again, referring to Fig. 2, the current path 2 (schematically shown with orange arrows) is the current path from the first electrical interface 144 to the second end 102 of the first core 110 when the connecting piece 145 is provided. It can be seen that in this case, the current path is significantly shortened and approaches, preferably equals, the current path from the first electrical interface 144 to the second end 102 of the third core 130. Here, the current path from the first electrical interface 144 to the first core 110 via the first section 141, the third section 143 and the second section 142 is defined as the first current path 1 (red arrows), and the current path from the first electrical interface 144 to the third core 130 via the first section 141 and the connecting piece 145 is defined as the second current path 2 (orange arrows). In one embodiment of the present application, the connecting piece 145 is arranged such that the length difference between the first current path 1 and the second current path 2 is less than or equal to 15% of the length of the first current path 1, and more preferably arranged such that the first current path 1 and the second current path 2 are equal in length, so that the first electrical interface 144 has equal length current paths to the first core 110 and the third core 130, and the current flowing in or out of the first electrical interface 144 can be evenly distributed between the first core 110 and the third core 130. Figure 2 , Figure 2

[0028] ​It should be understood that the “first current path 1 and the second current path 2 are of equal length” mentioned here means that the relationship between the second current path 2 and the first current path 1 is set so that the time and current intensity for the current to flow from the first electrical interface 144 to the first core 110 through the first current path 1 and from the first electrical interface 144 to the third core 130 through the second current path 2 are roughly equal, so that the current flowing into or out of the first electrical interface 144 can be evenly distributed between the first core 110 and the third core 130, and does not mean that the geometric straight-line distances from the first electrical interface 144 along the first section 141, the third section 143 and the second section 142 to the first core 110 and from the first electrical interface 144 through the first section 141 and the connecting piece 145 to the third core 130 are strictly equal. Figure 2 The red, yellow and orange arrows in the figure are only used to schematically illustrate the flow path of the current.

[0029] By providing the connecting piece 145, the current flowing into the first battery cell 110 and the third battery cell 130 through the first electrical interface 144 can be evenly distributed, thereby preventing the problem of excessive hot spot temperature caused by excessive current load of the first battery cell 110 and the second battery cell 130, thereby improving the working efficiency of the thin film capacitor 10.

[0030] In one embodiment of the present application, for example, Figure 2 In the embodiment, the connecting piece 145 is arranged at the core farthest from the first electrical interface 144 (at Figure 2 In this embodiment, the connecting piece 145 is disposed on the side surface 132 adjacent to the first side surface 131 of the third core 130. In other words, the connecting piece 145 extends through the side surface 132 of the third core. In this embodiment, the connecting piece 145 is disposed on this side surface 132, providing a "shortcut" for the current to flow to the second end 102 of the third core 130. In some embodiments, the first busbar 140 is integrally stamped from a metal plate (e.g., Figure 1 In the embodiment, during assembly, the connecting piece 145 is bent from the first end 101 of the third core 130 to the second end 102 of the third core 130 on the side surface 132 adjacent to the first side surface 131 of the third core 130. In other words, it is bent from the first section 141 of the first busbar 140 and then connected to the second end 102. For the structure of known thin-film capacitors, this design approach does not require changing the overall structure of the busbar. It simply adds the connecting piece 145 to the original structure of the first busbar 140, resulting in a simple and low-cost structure. It can also improve the heat dissipation capacity of the first busbar 140 without substantially increasing the volume of the thin-film capacitor 10.

[0031] The structure of the thin film capacitor 10 is described above in the form of a thin film capacitor unit 100. It should be understood that the thin film capacitor 10 may also include two thin film capacitor units or multiple thin film capacitor units. Figure 1 In the embodiment, the film capacitor 10 includes two film capacitor units 100 and 200 arranged symmetrically side by side, that is, it includes two groups of cores arranged side by side, each group of cores includes three cores arranged side by side, and each group of cores is paired with a first busbar 140 and a second busbar 150. The two groups of cores are arranged side by side in the same direction, for example, the first direction, and the film capacitor units 100 and 200 formed by each group of cores and their paired first busbar 140 and second busbar 150 are arranged symmetrically. The second busbars 150 of the two groups of cores are connected via second electrical interfaces 151 and 152, and the first busbars 140 of the two groups of cores are connected via a first electrical interface 144. Through this symmetrical arrangement and the shared electrical interface, the current flowing into the capacitor 10 from the first electrical interface 144 and the second electrical interface 151, 152 can be more evenly distributed to the two groups of 6 cores in total, shortening and balancing the current path from each electrical interface to the cores in the two thin film capacitor units 100, 200 as much as possible, thereby improving the working efficiency of the thin film capacitor 10 while ensuring that the thin film capacitor 10 can have a larger capacitance.

[0032] It should be understood that, in an embodiment not shown, each set of cores may also include two cores or a plurality of cores. In this case, those skilled in the art may refer to Figure 1 The thin film capacitor unit 100 formed by the cores and the first busbar 140 and the second busbar 150 paired with each group of cores is arranged in an arrangement manner.

[0033] In one embodiment of the present application, for example Figure 1 As shown, the second electrical interfaces 151, 152 are arranged on the edge of the main section 153 of the second busbar 150, and the first electrical interface 144 is arranged on the edge of the first section 141 of the first busbar 140, so as to facilitate connecting the two film capacitor units 100, 200 through the second electrical interfaces 151, 152 and the first electrical interface 144. Further, in one embodiment of the present application, for example, referring to Figure 1In this embodiment, two second electrical interfaces 151 and 152 are provided. These are arranged in the same direction as the side-by-side arrangement of the three cores, that is, also arranged side by side along the first direction described above, on both sides of the first electrical interface 144. As mentioned above, when the number of cores in each group is small, the difference in the current path from the second electrical interfaces 151 and 152 to the first end 101 of the cores is small. Therefore, no additional connection piece 145 or other electrical connector is provided to adjust the current path from the second electrical interfaces 151 and 152 to the individual cores. However, since there are differences in the current paths from the second electrical interfaces 151 and 152 to the first end 101 of the core, by setting two second electrical interfaces 151 and 152, the current path differences from the second electrical interfaces 151 and 152 to the first ends 101 of the three cores can be further optimized, so that the current flowing into or out of the second electrical interfaces 151 and 152 is more evenly distributed among the three cores. In this way, there is no need to additionally set up electrical connectors such as the connecting piece 145 to adjust the current path from the second electrical interfaces 151 and 152 to the core.

[0034] It should be understood that, based on the basic parameters of the capacitor, such as the number of cells, rated current, etc., those skilled in the art may also provide more than two second electrical interfaces 151, 152 to adjust the current distribution among the multiple cells. Similarly, two or more first electrical interfaces 144 may be provided to adjust the current distribution among the multiple cells. Multiple first electrical interfaces 144 may also be provided in combination with the connecting piece 145 to further facilitate current distribution among the cells when the film capacitor 10 has a large number of cells, for example, more than four cells.

[0035] In one embodiment of the present application, an opening 146 is provided on the first section 141 of the first busbar 140, and a second welding portion 154, such as a welding spot or welding pin, is provided at a position on the second busbar 150 corresponding to the opening 146. The second busbar 150 is welded to the first end 101 of the core via the second welding portion 154. The welding portion 154 is exposed through the opening 146, facilitating the welding operation between the second busbar 150 and the core from outside the film capacitor 10. Figure 3 , which shows a view of a film capacitor according to one embodiment of the present application viewed from another direction. Figure 3 As can be seen in the figure, the second section 142 of the first busbar 140 is welded to the second end 102 of the core via a first welding portion 147, such as a welding spot or welding pin. The connecting piece 145 is welded to the second end 102 of the third core 130 via a third welding portion 148, such as a welding spot or welding pin. The connecting piece 145 is particularly welded to the area of ​​the second end of the third core 130 that is not covered by the second section 142 and the first welding portion 147.

[0036] It should be understood that in an embodiment not shown, the connecting piece 145 may also be connected, in particular welded, to the second section 142 of the first busbar 140 , thereby being indirectly connected to the second end 102 of the core via the first weld 147 .

[0037] It should be understood that all the above preferred embodiments are illustrative rather than restrictive, and that various modifications or variations made by those skilled in the art to the specific embodiments described above based on the concept of this application should be within the legal protection scope of this application.

Claims

1. A film capacitor, characterized in that: include: at least two cores arranged side by side, each core having opposing first and second ends and a side extending between the first and second ends, an electrode disposed on the second end; a conductive first busbar comprising a first electrical interface, a first section, a second section, a third section, and a connecting piece, wherein the first section covers the first end and is connected between the first electrical interface and the third section, the second section covers the second end and is electrically connected to the electrode on the second end, and the third section covers one side of the core and is connected between the first section and the second section; The connecting piece connects the first section and the electrode at the second end of the core farthest from the first electrical interface and extends through a side surface of the core farthest from the first electrical interface. The connecting piece is spaced apart from the third section.

2. The film capacitor according to claim 1, wherein An electrode is arranged on the first end of the core, and the thin film capacitor also includes a conductive second busbar, which includes a main body section and a second electrical interface connected to the main body section. The main body section is electrically connected to the electrode at the first end of the core and is arranged under the first section.

3. The film capacitor according to claim 2, wherein: The current path of the current from the first electrical interface through the first section, the third section and the second section to the core closest to the first electrical interface is the first current path, and the current path of the current from the first electrical interface through the first section and the connecting piece to the core farthest from the first electrical interface is the second current path. The connecting piece is configured so that the difference in length between the first current path and the second current path is less than or equal to 15% of the length of the first current path.

4. The film capacitor according to claim 2, wherein: The core includes a first core, a second core, and a third core arranged side by side along a first direction, the first electrical interface is arranged close to the first core, and the connecting piece extends through a side surface of the third core.

5. The film capacitor according to claim 4, wherein: There are two second electrical interfaces, which are respectively arranged on both sides of the first electrical interface along the first direction.

6. The film capacitor according to any one of claims 2 to 5, characterized in that: The film capacitor includes two groups of cores arranged side by side, each group of cores includes at least two cores arranged side by side and each group of cores is provided with a paired first busbar and a second busbar, the first busbars of the two groups of cores are connected through the first electrical interface, and the second busbars of the two groups of cores are connected through the second electrical interface.

7. The film capacitor according to claim 2, wherein: An insulating layer is sandwiched between the first busbar and the second busbar.

8. The film capacitor according to claim 2, wherein: An opening is provided on the first section of the first busbar, a welding portion is provided at a position on the second busbar corresponding to the opening, and the second busbar is connected to the first end of the core through the welding portion.

9. The film capacitor according to claim 1, wherein The first busbar is integrally stamped from a metal plate.

10. The film capacitor according to claim 1, wherein The second end is entirely configured as an electrode, the third section is welded to the second end, and the connecting piece is welded to an area of ​​the second end that is not covered by the third section.

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